Haemocytometer pipette



Jan. 26, 1954 s. M. VIHITEHILL ET AL 2, 7,074

HAEMOCYTOMETER PIPETTE Filed May 9, 1952 2 SheetsSheet l 4 2" INVENTORS. 34 ,4- 6 Jrmvqsy/i W/wrEH/u.

[6' 5650 if dear/Y J 26, 1954 s. M. WHITEHILL ETAL 2,667,074

HAEMOCYTOMETER PIPETTE 2 Sheets-Sheet 2 Filed May 9, 1952 Patented Jan. 26, 1954 UNITED STATES PATENT OFFICE HAEMQCYTOMETER 'PIPET'I'E Stanley M. Whitehill and Fred A. Groth,

Chicago, 111

Application May 9, 1952, Serial No. 286,904

3 Claims.

of the article with a gauge line indicating 20 cubic millimeters adjacent the opposite end. Other types, such as blood dilution pipettes, include a bulbous dome on the surface of the pipette which contains a loose bead so blood and other chemicals may be drawn into the chamber, and by shaking the article the bead acts as an agitator to dilute and mix the blood and chemicals.

In the past these pipettes have been made or" glass by a glass-blowing process to form the tube with a narrow opening at the pointed end. After the article has been made, exactly 20 cmm. of liquid is drawn into the passageway in the tube, and the gauge line indicating this point is inscribed or printed on the surface to show the height of liquid at 20 cmm. Since the cross-sectional area of the passageway is not constant nor the same in any given number of pipettes, each one must be individually filled and the 20 cmin. gauge line inscribed. This consumes considerable time and as a result the glass pipettes are comparatively expensive. For this reason they are washed, sterilized and used over again and again. Our invention contemplates the provision of a disposable pipette of plastic that is easily and cheaply made, one that is absolutely accurate in measurements and wherein the reading gauge or other indiciurn is embossed on the surface of the article during its manufacture, so that all will be identical.

A further object is to provide an improved pipette or similar device capable of manufacture in quantity whereby the passageway therein is of constant size in all, so that indicator gauge lines thereon may be made by embossments in the dies of the molds, and the location of the same will be identical in all.

A. further object of the invention is to provide a pipette or similar devices so cheaply that the same can be made in large quantities and supplied to doctors, nurses and. other users as a disposable or one time use item.

Other advantages of the pipette reside inthe construction of the molds, process of molding, assembly of parts and the accuracy of the com: pleted combination, as will be more apparent from the following description wherein reference is had to the accompanying drawings, upon which (Cl. lit-425.4)

Fig. 1 is afront perspective view of a haemocytometer pipette of the type to which we refer, being shown connected to the usual rubber hose and suction tube that is used;

Fig. 2 is a fragmentary cross-sectional view showing the molds and the top strip therein;

Fig. 3 is a similar cross-sectional View showing the molds and the bottom strip therein;

Fig. 4 is a cross-sectional View on the line l-4 of Fig, 1 showing the manner in which the two parts are fused together to form the passageway therein;

Fig. 4a is a similar cross-sectional view of a modified form of construction showing an arcuate passageway;

Fig. 5 is a plan view of a pipette foreshortened to show both ends of the same;

Fig. 6 is a side elevational view thereof;

Fig. 7 is a front perspective view of a modified form of pipette of the type that is used for blood dilution;

Fig. 8 is a cross-sectional view of the molds with the lower strip in the same;

Fig. '9 is a cross-sectional View showing the molds with the upper strip in the same;

Fig. 10 is a cross-sectional view showing the molds at the point where the bulbous dome is formed on the pipette;

Fig. 11 is'a side elevational view of the same: and

Fig. 12 is a cross-sectional view thereof taken on the line lZ-IZ of Fig. 11.

In the embodiment of the invention which we have chosen to illustrate and describe the same, in Fig. 1 we have shown a pipette Iii in the usual form in which they are made, with the pointed lower end l2 and an upper end I l to which a rubber hose E 6 may be'attached, the hose having a. suction tube It at the end of the same. The pipette is provided with an index mark I and the imprinting 2t CMM at the point on the pipette where the passageway therein will hold exactly 20 cmm. of fluid. Since this is a critical quantity, in the past all blood pipettes have been tested for'accuracy and the marking-placed on the tube in accordance with the test. The method which we employ to make pipettes will now be described.

In Fig. 2 we have shown the upperand lower mold sections 20 and 22 within which the upper or top strip 2 3 is molded. It will be noted that the top surface of the same is formed in an arouate curve '26 and the lower surface 28 is formed with a pair of spaced parallel rails 30, leaving a groove 32 therebetween.

The bottom strip 34 may be formed in a pair of mold sections 36 and 38, the strip having a a pair of upwardly extending ledges 46 with a groove 4| therebetween. After the two strips hav been molded, a suitable acid is applied to the top of ledges 49 and the bottom wall 28 of the strip 26 to fuse the two parts of the tube together. After this has been done, a passageway 42 is formed in the tube, the passageway being absolutely accurate throughout its length.

Since the passageway is accurate, the mold may have the index mark I and the legend 29 CMM therein, so that as the upper strip is molded the indicia will be embossed on the top surface of the same. With this method of manufacture every pipette will be identical with others, and thousands of the article may be made in the same molds, and when they are fused together as described accurate and absolutely dependable pipettes have been produced.

In the embodiment of the invention shown in Figs. 7 to 12, we have shown a pipette 59 of the type that is used for effecting blood dilution. The pipette 59 may also be formed with the pointed lower end 52, a bulbous dome 54 adjacent the upper end and indicia marks 56 on the upper surface of the same. The dome 54 has a chamber 58 therein which contains a bead 69 or similar object that is used for agitating blood and chemicals that are drawn into the chamber.

In manufacturing pipettes of this type, we employ mold members 62 and 64 to form the bottom strip 66, the strip being formed with a pair of upstanding edge ledges 68 and a medial groove 19 therebetween. The top strip i2 may be formed as shown with the bottom wall it and a pair of parallel rails 76 which form a medial groove 78 therebetween. At the dome 54 the lower mold 89 may be formed with an upstanding arcuate portion 82 to form the dome-shaped portion d of the upper strip 72. The mold may also be indented with the indicia so that as th strip 55 is made, the indicia 56 will be embossed on the surface of the same.

As previously described, the plastic strips E2 and 66 may now be fused together by applying acid on the upper surface of the ledges 68 and the bottom wall 74 of the upper ledge 62 on the outside of the rails 76. In this way the tube strips are quickly fused togethe and an accurate passageway and dome are formed therein. The bead 60 is of course applied before the two strips are fused together.

While we prefer to use a plastic such as acrylic plastic, and ethylene dichloride for fusing the same together, it will be understood that other suitable types of plastics and fusing acids or chemicals may be employed. Acrylic plastic is preferable in that reflection of light is easily obtained so that the indicia on the same can be easily read.

From the above and foregoing description it can be seen that we have provided a method of manufacturing haemocytometer pipettes easily and cheaply, and whereby the same may be made in large quantities with each one accurate and dependable. Due to the fact that no testing or measuring is necessary for applying the idicia on the upper strip, the indicia, are applied as the strip is molded, so that each pipette will be identical with all the rest. Due to the cheapness of manufacture, the pipettes may be manufactured, sterilized, placed in a sealed envelope, and be disposable after a single use. In addition, breakage due to dropping or other causes is eliminated, and the insertion of the bead or agitator is easily accomplished.

While we have illustrated and described a specific embodiment of the invention, it will be apparent to those skilled in the art that changes and modifications may be made in the exact details shown, and we do not wish to be limited in any particular; rather what we desire to secure and protect by Letters Patent of the United States is:

1. A haemocytometer pipette made of a transparent plastic material consisting of an elongated top strip having a rounded top surface and a bottom surface having a pair of parallel rails with a flat medial groove therebetween extending the length of the bottom surface, an elongated bottom strip having a pair of parallel upper ledges embracing said parallel rails, said strip having a flat medial groove therein between said ledges extending the length of the top surface of the same, the contacting surfaces of said strips being bonded together, said top strip having a tapered point at one end and gauge indicia adjacent its other end.

2. An article of manufacture comprising an elongated stem formed of two parts of a transparent plastic material fastened together and consisting of an upper part having an arcuate top wall and a flat bottom wall, the bottom wall having an elongated groove therein, and a lower part having a fiat bottom wall and a flat top wall having an elongated groove therein, the contacting surfaces of said parts being bonded together,

=. said parts when fastened together forming a passageway therein throughout the length of said stem, said upper part having a tapered point at one end and gauge indicia adjacent its other end.

3. An article of manufacture comprising an elongated stem formed of two parts of a transparent plastic material fastened together and consisting of an upper part having an arcuate top wall and a flat bottom wall, the bottom wall having an elongated groove therein, and a lower part having a flat bottom wall and a flat top wall having an elongated groove therein, the contacting surfaces of said parts being bonded together, said parts when fastened together forming a passageway therein throughout the length of said stem, said upper part having a tapered point at one end and gauge indicia adjacent its other end, a bulbous dome being formed in said top wall at its end opposite to its tapered point.

STANLEY M. WHITEHIIL. FRED A. GROTH.

References Gited in the file of this patent UNITED STATES PATENTS 

